What percentage of us water sources are considered to be polluted?

As published in EPA's national water quality inventory report,
 
40 Percent of rivers and 46 % of lake are considered to be plluted. these sources, called the surface water are vulnerable to pollution discharged of pipesand runof pollutants washing off the lands.

These sources are extremely unsafe to drink and to swim in

The scientist can conclude that there is a decrease in the natural resources due to human activities. because of innovation and modernization of the environment, then there goes pollution and other bad effects that destroys the natural resources.